Modular sealed portable digital electronic controller

ABSTRACT

An electronic digital controller, such as a load cell indicator, is disclosed in which a number of components, such as a circuit board, display, and keypad are placed within an enclosure, and the enclosure is bonded closed, such as using an adhesive, to render the enclosure watertight. The keypad is a touch sensitive, capacitive keypad with no moving parts, and it is housed behind a rigid panel. An optoelectronic transceiver allows for data exchange with an electronic memory device housed in the adhesively sealed enclosure and allows for data exchange and for updating or modification of software code housed therein. Other components, such as another circuit board, a power supply, and block connectors, are placed in an adjacent enclosure, and the circuit boards in the two enclosures are electrically connected. The power supply is preferably a potted AC power supply but may also include a battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 11/198,110 filed on Aug. 5, 2005 and having the inventorsTimothy R. Cox, et al., which claims benefit of U.S. patent applicationSer. No. 10/345,566 filed Jan. 16, 2003, now U.S. Pat. No. 7,002,084issued on Feb. 21, 2006, which claims benefit of U.S. Provisional PatentApplication Ser. No. 60/350,297 filed Jan. 16, 2002. Each of theaforementioned related patent applications and patents is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to digital electronic controllers and, moreparticularly, to portable digital electronic load cell indicators.

Measuring transducers are known in the art and are used to measureforces associated with any number of applications involving such thingsas weight, gravity, pressure, and vibration. A load cell is a commonmeasuring transducer that is typically used in a wide variety of scalesor weighing systems. A load cell typically generates an analog signalthat is converted to a digital signal before being displayed orotherwise processed or used. An electronic controller, such as a loadcell indicator, is typically used to display data received from a loadcell and is often used to convert the data from analog to digital formatbefore the data is displayed or used.

Load cell indicators are well known. Most have common weaknesses thatpresent problems particularly when the load cell indicators are used inrough, washdown environments. In some environments, such as poultryprocessing facilities, the indicators may be handled roughly and withdisdain. Cleaning crews may aim high pressure spray guns spraying hotcleaning solution at electronic instruments for sport. This highpressure spray will often seep past gaskets and seals, leaving theinternal electrical connectors and electronic components wet. Since thecleaning solutions used are typically slightly conductive, any solutionthat finds its way to the incoming AC power connector will often resultin damage, which can range from minor corrosion of wiring and printedcircuit board traces to arc-over and destruction of the AC powerconnector and related circuitry. This damage often limits the usefullife of an instrument to mere weeks.

The personnel using the indicator as part of their daily job functionmay also be handling sharp pointed instruments, such as knives orscissors. They quite often use the sharp instrument instead of a fingerto press buttons on a keypad. If the indicator uses a plastic membranekeypad, which is by far the most common type of front panel found onload cell indicators, this activity will quickly result in a damagedkeypad. Depending on the design on the specific indicator, a damagedkeypad may be replaced, or it may mean replacement of the entireindicator. Again, this potential for damage limits the lifetime ofindicators in some environments.

To prevent damage from the user or the environment, some load cellindicators are mounted inside another enclosure, often with a latchingflip-up transparent front lid, allowing the user to see the display. Toaccess any of the front panel controls, the user must first unlatch thelid, lift it up, and finally press the desired key. While this style ofdouble enclosure mounting may reduce high pressure fluid infiltration inthe indicator enclosure, it also limits operator access to theindicator, sometimes excessively so. The effectiveness of this mountingstyle is frequently reduced by the tendency of operators to forget tolatch the front lid, leaving the indicator exposed to the very highpressure spray the lid was intended to prevent.

Most digital load cell indicators have some type of display to presentweight information to the user. The choice of display can beproblematic, as many display types with outstanding visibility (such asa vacuum florescent display—VFD) have high power consumption. Indicatorsthat use VFDs often have no provision for running from battery power,limiting their usefulness as a portable device. Other indicators useseven-segment light emitting diode (LED) displays, which provide goodvisibility and reasonable power consumption, but the seven-segment styleof digit is not conducive to presenting alphanumeric data to the user.Indicators with seven segment displays are thus limited in displayinginformation, which makes setup and troubleshooting cryptic anddifficult. LCD (liquid crystal display) technology is also used in loadcell indicators. LCDs are very low power consumption devices. LCDs arealso available in character mode and dot-matrix configurations, whichallow the presentation of alphanumeric data and even graphic informationin an easily readable style. However, many digital load cell indicatorsuse LCD modules that require ambient light for the display to be visibleto the user, which makes the instrument difficult to use in dark oruncertain lighting.

Load cell indicators designed for use in washdown environments are oftenhoused in stainless steel enclosures to resist corrosion. Hightemperature washdown followed by extended use in cold temperatureenvironments can lead to condensation forming on the enclosure. If theseals around the cables, display, and keypad are less than perfect, andthey usually are, condensation can also form on the inside of theenclosure, which can wet the electronic components, circuit boards, andconnectors. Display fogging is also common in this situation. Theseconditions conspire to limit the effectiveness of the indicator.

Load cell indicator enclosures designed for washdown environments aresometimes designed with many closely-spaced fasteners and gaskets toprevent or reduce high pressure fluid infiltration. If internal accessto the enclosure is desired, such as to replace a load cell cable orpower cable, the technician performing the procedure will spend quite abit of time and frustration removing all the fasteners and sealingmaterial to gain access to the internal connections of the indicator.

Very few load cell indicators are designed to interface with more thanone independent load cell. This limitation leads to the use of externalhardware, such as summing boxes, to condition multiple load cell signals(as might be provided by a large tank or platform scale) for use withcommon indicators. Summing boxes are generally passive devices, withpotentiometers that must be manually adjusted to ensure that each loadcell contributes equally to the summed analog signal. It is not uncommonfor a scale technician to spend hours manually adjusting a single loadcell summing box to allow an indicator to accurately weigh whenconnected to a multiple load cell platform.

Some load cell indicators have provisions for interfacing with otherinstruments, such as bar code label printers, data collection devices,or computer hardware. This connection is often through a serialcommunications port. Depending on the requirement of the user, the datatransfer format between the load cell indicator and other auxiliaryinstruments, may have to be customized to the user's specificinstallation and circumstances. For many load cell indicators, this issimply not possible, as there is no allowance for field customization ofthe software code contained inside the indicator controller, and themanufacturers are unable to update software once the indicator has beenmanufactured.

Advanced or high-end load cell indicators may be used as weighingmachine controllers, in which case they are often integrated into other,more complicated machines. These machines might consist of several loadcells, other load cell indicators, various valves, slides, gates, andmotor drives, sometimes from a diverse group of manufacturers. Duringintegration and testing, problems, bugs, or unforeseen circumstanceswill often arise that require the machine controller software to bemodified. If the advanced load cell indicator/controller is not designedwith this in mind, the upgrade might require significant disassembly ofthe indicator and associated hardware to replace a physical electronicdevice containing the controller software.

Many users of load cell indicators desire a small, portable instrumentthat can be mounted on a load cell platform and that can be carried byhand. This requirement limits the overall size and weight of theinstrument and also requires a portable power source, such as a battery.Many load cell indicators do not have any provision for a battery. Somedo, but require so much power that the only practical option is aphysically large battery mounted external to the indicator enclosure.Any externally mounted battery will require wiring to provide power tothe indicator, and that wiring introduces at least two additionalweaknesses into the system: the wiring must be sealed to prevent leakagewhere it enters the indicator enclosure, and exposed wiring isvulnerable to damage.

Load cell indicators used in harsh environments are often damaged. Whenthis occurs, many users will desire to troubleshoot the indicator todetermine the cause of the failure, and then will often elect to attempta repair. Load cell indicators are relatively complicated and includedelicate electronic instruments, so troubleshooting may call for the useof skilled electronic technicians and other highly trained and costlypersonnel equipped with an assortment of specialized tools. If theindicator does not have adequate documentation or if spare parts are noteasily available, it may be more economical to replace the entireindicator rather than to repair it. A user or technician who may attempttroubleshooting but who may lack the proper training or the right toolscan often do more harm than good when provided with ready access to allof the electronic components of these relatively complex, delicateinstruments.

All load cell indicators will require calibration to accurately weighwhen interfaced with a specific load cell. Indicators are alsocalibrated at regular periods of time to meet various legal, trade, andinternal requirements. Many load cell indicators are difficult tocalibrate. The indicator calibration procedure may require variousinternal switches and potentiometers to be manually adjusted in a veryfine and precise manner. The calibration procedure may require an exactvalue of weight to be applied to the scale. Some indicators have arather lengthy and complicated calibration procedure that is not obviouswithout supplemental documentation, so if the calibration procedureinstructions are misplaced, that scale is unusable.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a digitalelectronic controller, such as a load cell indicator, that isparticularly suited for use in a harsh washdown environment.

It is a further object of the present invention to provide a load cellindicator of the above type that protects many key, sensitive componentsof the indicator by permanently sealing them within a watertightenclosure such as by using an adhesive seal.

It is a further object of the present invention to provide a load cellindicator of the above type that protects against moisture coming intocontact with high voltage within the indicator.

It is a further object of the present invention to provide a load cellindicator of the above type that reduces the risk of damage to a keypadused in connection with the indicator.

It is a still further object of the present invention to provide a loadcell indicator of the above type that eliminates the keypad as apossible point entry for water or moisture.

It is a still further object of the present invention to provide a loadcell indicator of the above type that allows a user access to the keypadwithout the need to open or close a lid or separate housing.

It is a still further object of the present invention to provide a loadcell indicator of the above type having a display that offers very lowpower consumption while allowing the presentation of alphanumeric dataand graphic information in an easily readable style in a variety oflighting conditions.

It is a still further object of the present invention to provide a loadcell indicator of the above type that eliminates or greatly reducesproblems associated with display fogging.

It is a still further object of the present invention to provide a loadcell indicator of the above type that provides superior protectionagainst water infiltration while providing easy access to a number ofits components.

It is a still further object of the present invention to provide a loadcell indicator of the above type that eliminates the need for externalsumming circuits or boxes or analog to digital converters.

It is a still further object of the present invention to provide a loadcell indicator of the above type that protects many key, sensitivecomponents of the indicator by adhesively sealing them within awatertight enclosure.

It is a still further object of the present invention to provide a loadcell indicator of the above type that provides for easy customizationand updating of software code inside the indicator and for easy datatransfer to and from the indicator without the need to gain physicalaccess to any indicator enclosure.

It is a still further object of the present invention to provide a loadcell indicator of the above type that provides for easy calibration ofthe indicator without the need to gain physical access to any indicatorenclosure.

It is a still further object of the present invention to provide a loadcell indicator of the above type that may be powered by AC power or byan internal battery.

It is a still further object of the present invention to provide a loadcell indicator of the above type that provides users with ready accessto some components of the indicator for easy installation andmaintenance and some troubleshooting while protectively sealing othercomponents in an inaccessible enclosure.

Toward the fulfillment of these and other objects and advantages, thepresent invention involves an electronic digital controller, such as aload cell indicator, in which a number of components, such as a circuitboard, display, and keypad are placed within an enclosure, and theenclosure is bonded closed, such as using an adhesive, to render theenclosure watertight. The keypad is a touch sensitive, capacitive keypadwith no moving parts, and it is housed behind a rigid panel. Anoptoelectronic transceiver allows for data exchange with an electronicmemory device housed in the adhesively sealed enclosure and allows fordata exchange and for updating or modification of software code housedtherein. Other components, such as another circuit board, a powersupply, and block connectors, are placed in an adjacent enclosure, andthe circuit boards in the two enclosures are electrically connected. Thepower supply is preferably a potted AC power supply but may also includea battery.

BRIEF DESCRIPTION OF THE DRAWINGS

The above brief description, as well as further objects, features andadvantages of the present invention will be more fully appreciated byreference to the following detailed description of the presentlypreferred but nonetheless illustrative embodiments in accordance withthe present invention when taken in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a side elevation view of a load cell indicator of the presentinvention;

FIG. 2 is a sectional view of a load cell indicator of the presentinvention;

FIG. 3 is a side elevation view of a partially disassembled frontenclosure of a load cell indicator of the present invention;

FIG. 4 is a front view of a partially disassembled rear enclosure of aload cell indicator of the present invention; and

FIG. 5 is a front view of a partially disassembled rear enclosure of analternate embodiment of a load cell indicator of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the reference numeral 10 refers in general to anelectronic digital controller, such as a load cell indicator, of thepresent invention. The indicator 10 has a housing 12 comprised of afront cover 14, a base 16, and a rear cover 18 that are formed frommolded plastic and that fit together to form front and rear enclosures20 and 22 that house various components of the indicator 10.

The front cover 14 is formed by a front panel 24 and a side panel orbezel 26. The front panel 24 is produced from a transparent, rigidplastic to allow a display 28 and front panel legends 30 to be visiblefrom outside the enclosure. The front panel 24 also has one or moreareas of reduced thickness 32 aligned with keys or touch sensitive areasof a keypad 33 disposed inside the front enclosure 20. The areas ofreduced thickness 32 are formed integrally with the remaining portion ofthe front panel 24 and are also rigid. The front panel 24 is bonded,such as by adhesive bonding, to the side panel 26 about substantiallyits entire perimeter to form a watertight seal. The side panel 26 isbonded to both the front panel 24 and the base 16. A back edge of theside panel 26 and front surface of the base 16 mate together with atongue and groove fitting, and the side panel 26 is bonded to the base16 about substantially the entire perimeter of the tongue and groovefitting to form a watertight seal. It is of course understood that thefront cover 14 may be formed as a single piece or as any number ofdifferent pieces and that it may take any number of different shapes,sizes, or configurations. As used herein, it is understood that the term“bond” or “bonding” encompasses a variety of different methods offorming a watertight seal between two joined work pieces, including butnot limited to the use of adhesives or welding. For example, any numberof different adhesives may be used, including but not limited to a widevariety of glues, resins, epoxies, tapes, or foams. Similarly, anynumber of different welding techniques may be used, including but notlimited to ordinary welding, ultrasonic welding, and solvent welding.

The base 16 has any number of bosses 34 extending from its front surfacefor securing various components to be housed in the front enclosure 20.For reasons to be described, a chute 36 is formed integrally with andextends from a rear surface of the base 16. A back edge of the base 16and a front edge of the rear cover 18 mate together with a tongue andgroove fitting. A gasket, O-ring, or similar sealing members are used incombination with the tongue and groove fitting to provide a waterresistant seal. Holes 38 pass through an outer periphery of the base 16,disposed outward of the tongue and groove fittings so that the holes 38do not provide points of entry into either enclosure. Captive screwfasteners 40 pass through the holes 38 and are captively retained by thebase 16. The front panel 24, side panel 26, and base 16 form and boundthe front enclosure 20. These components are permanently bonded andsealed to prevent any fluid infiltration into the front enclosure 20,and the front cover 14 and base 16 are adapted so that a user may notgain physical entry to the front enclosure 20 without breaking, cutting,or otherwise piercing the base 16 or front cover 14. Similarly, theadhesive selected preferably will not allow a user to overcome theadhesive bond to gain physical access to the front enclosure 20 and willinstead require a user to break, cut, or otherwise pierce the base 16 orfront cover 14 to gain physical entry to the front enclosure 20.

The rear cover 18 has one or more openings or ports 42 along its sidesor back surface to provide one or more points of entry into the rearenclosure 22 for things such as an AC power cord 44, wires or cables 46from load cells 48, and any number of other types of optionalcommunications cabling, such as to a printer, computer, another loadcell indicator, remote display, or other peripheral hardware. Seals,gaskets, or any other number of water resistant closures 50 may be usedin combination with these ports 42 to keep moisture from entering therear enclosure 22. The rear cover 18 has any number of bosses 34extending from one or more of its inner surfaces for securing variouscomponents to be housed in the rear enclosure 22. Inner partitions 52also extend from one or more inner surfaces of the rear cover 18 toprovide for further isolation of components in the rear enclosure 22.Threaded bores or holes 54 pass through an outer periphery of the rearcover 18, disposed outward of the tongue and groove fitting so that thebores 54 do not provide points of entry into the rear enclosure 22. Thethreaded bores 54 provide locations for attachment of the screwfasteners 40 so that the fasteners 40 may provide for compression of theO-ring type sealing gasket. The rear surface of the rear cover 18 alsohas a plurality of threaded bores to provide means for attaching theindicator 10 to external panels, braces, or the like 56. These threadedbores do not open into the rear enclosure 22 so that they do not providepossible locations for moisture to enter into the rear enclosure 22. Therear cover 18 and base 16 form and bound the rear enclosure 22.

The front enclosure 20 contains the majority of the electronics for theindicator 10, such as the main circuit board 58, display 28, keypad 33,microprocessor 59, electronic memory device, optoelectronic transceiver60, analog to digital converter, and the like. The main circuit board 58is affixed to bosses 34. Since the front enclosure 20 is sealed, and thefront panel 24 is formed of a rigid plastic, there is no provision foran industry standard membrane keypad or mechanical switches. A thinopaque pre-printed polycarbonate graphic legend 30 is attached with anoptically clear adhesive to the inside of the front panel 24. Thisgraphic legend 30 provides for front panel 24 nomenclature, which mayinclude such information as a stylized company and product logo, modelname or number, keypad button descriptions, and labels for the variousLED indicators. The graphic layer has a window cutout 62 to allow thedisplay 28 to be visible. It is of course understood that the graphiclegend 30 may be printed directly onto the front panel 24.

Adhered to the graphic legend plastic is the touch sensitive keypad 33circuit board, preferably a capacitive, touch sensitive keyboard 33circuit board. One side of this keypad 33 circuit board, which isattached to the graphic layer, is composed of five conductive sensingareas that serve as the touch sensitive buttons. The other side of thekeypad 33 circuit board contains the surface mount electroniccomponents, which sense the absence or presence of a finger andtranslate this to the main circuit board 58 as a key press. In thismanner, the user can simply touch his finger against certain spots onthe outside of the front panel 24 to initiate a key press. Because thiskeypad 33 contains no moving parts, and the electronic components of thekeypad 33 are located inside the sealed front enclosure 20, it cannot beeasily damaged or worn out. Although a capacitive touch sensitive keypad33 is preferred, other touch sensitive keypads may be used, such as forexample a reflective optical sensing keypad, which detects whether ornot a person's finger is present on the sensing spot. Placing thegraphic legend 30 inside the transparent front panel 24 also serves toprotect the markings and nomenclature from abrasion and physical wear,and adhering the graphic legend 30 to the transparent front panel 24also reduces or eliminates fogging problems with respect to informationshown on the graphic legend 30. A small package 35 containingmoisture-absorbing desiccant material is also placed inside the frontenclosure 20 during assembly. The desiccant package 35 helps to ensurethat the air contained in the front enclosure 20 stays dry, whichprevents any condensation from occurring on the inside of thetransparent front panel 24.

The keypad 33 circuit board can also contain several small LEDs 64.Typically, these are lit to indicate scale operating parameters, such asnet, gross, or tare weight, weight in motion, or center of zero weight.When illuminated, the LEDs 64 are visible through the graphic legend 30layer.

The display 28, which is a backlit liquid crystal character mode dotmatrix display, is physically mounted by screw fasteners on four moldedbosses 34 of the base 16. It is electrically connected to the maincircuit board 58 by soldering during assembly of the indicator 10. Thedisplay 28 of the assembled indicator 10 is visible through thetransparent front panel 24 and the window cutout 62 of the graphiclegend 30 layer. Circuits on the main circuit board 58 and softwareroutines allow the user to adjust the backlight and contrast of thedisplay 28 for good visibility in all lighting conditions. The user mayalso elect to disable the backlight to conserve power and lengthen thebattery life.

An IrDA compliant optoelectronic transceiver 60 circuit is included onthe main circuit board 58. Together with other support circuitry on thecircuit board and software, this transceiver 60 allows for serialbidirectional infrared data communications with various externalhardware devices. This data communication protocol is optical andnon-contact, so the indicator user can initiate a data transfer with theindicator 10 by pointing a device such as a handheld personalcomputer/organizer at the indicator front panel 24 and executing theappropriate software routines.

An analog to digital converter component 66 is also included in thefront enclosure 20, electrically connected to the main circuit board 58.The converter 66 was chosen in part for its ability to connect tomultiple analog input signals. This allows for the option of interfacingwith multiple independent load cells 48. Software routines may bepresent to calibrate and compensate each load cell 48 signal independentof the other load cells. Software routines may also be present to sumthe signals digitally if necessary. If an application uses two or moreload cells 48 as independent sensors, and the indicator 10 is programmedto simulate multiple scales, applying a weight to one load cell 48 hasno effect on any other load cell 48 in the system. In this situation,summing is not needed. If an application uses multiple load cells 48attached to a common weighing device so that an object to be weighedwill deflect multiple load cells 48, the software routines may be usedto sum the inputs from the multiple load cells 48 and to calculate thetotal weight on the weighing device. In this type of application,software routines are present to calibrate and compensate each load cell48 signal independent of the other load cells. In most cases, theability to interface with multiple load cells 48 eliminates the need forexternal analog summing circuits or boxes. If a summing circuit or boxis used, software routines may also be provided that will serve as adigital replacement for an external analog summing circuit, eliminatingthe time-consuming drudgery of manually balancing load cell 48 inputssuch as from a floor scale weighing platform.

One or more electronic memory devices 68, such as a flash memory devicemay be provided in the front enclosure 20, electrically connected to themain circuit board 58, for storage of software programs and data. Withproper software routines, the memory device 68 can be easily erased andreprogrammed without disassembly. If the infrared data communicationschannel is used to transfer the new software to the indicator 10, theentire indicator software can be upgraded without error in the field bya technician or user in minutes.

A connector 70, such as a 30-pin dual row connector, is electricallyconnected to the main circuit board 58 and extends into the chute 36. Aportion of the connector 70 is exposed outside of the rear surface ofthe base 16 for mating connection with a connector 72 that is affixed toan interface circuit board 74. The chute 36 is sealed, such as with anepoxy or resin, which forms a watertight seal around the connector. Thechute 36 also has to protect the connector 70. In that regard, threegrooves are provided in the chute 36 that will only mate withcorresponding ramped tabs in the rear cover 18 if the two halves arecorrectly positioned. Any misalignment of the two halves will preventthe tabs and grooves from engaging. This, and the fact that the chute 36extends past the end of the connector 70 pins, protects the connector 70pins from damage.

It is of course understood that any number of different combinations ofcomponents may be disposed in the front enclosure 20 and that not allfeatures or elements discussed above need to be enclosed in the frontenclosure 20.

The physically accessible rear enclosure 22 contains components to whicha user will typically need access in the field. Because it is accessibleand not permanently sealed, it is purposely of simple design. Theinterface circuit board 74 is located in the rear enclosure 22. Further,a few components that will typically be disposed in the rear enclosure22, electrically connected to the interface circuit board 74, includeone or more terminal block style connectors 76 or rows of suchconnectors for external devices, and connectors 78 and 80 for the powersupply 82 and optional battery 84. The interface circuit board 74 canalso provide an LED indicator that illuminates when the power supply 82is energized, electrical components for transient voltage suppression,and optically isolated modules 88 for controlling external input andoutput devices. The connector 72 is also provided, electricallyconnected to the interface circuit board 74, for mating with theconnector 70. All electrical connections to the load cell indicator 10are made through the interface circuit board 74, which is mounted in therear enclosure 22. This interface circuit board 74 is accessible to theuser for wiring external devices by removing the sealed front half ofthe indicator 10.

A power supply 82 section is provided in an upper region of the rearenclosure 22 for receiving high voltage AC power and for providingappropriate voltage reduction. The power supply 82 section is set apartfrom other components in the rear enclosure 22 by the partitions 52. Thepower supply 82 section contains a watertight electrical connector thatextends through an opening in the back surface of the rear cover 18 forreceiving the incoming AC power supply (normally 120 VAC). To protectagainst moisture contacting any high voltage wiring inside the rearenclosure 22, the power supply 82 is potted in an electronic grade epoxy90. When the power supply cord 44 is attached, there is no exposed highvoltage (>24 VAC) within the rear enclosure 22 or front enclosure 20,which reduces the possibility of damage should moisture make its wayinto the indicator 10. Placing the power supply 82 in an upper region ofthe rear enclosure 22 also reduces the risk that water that may enterand gather in a bottom portion of the rear enclosure 22 will come intocontact with the power supply 82.

Because the indicator 10 is also intended for portable use, a sealedlead acid battery 84 may also be mounted in the rear enclosure 22,preferably in an upper region thereof. If a battery 84 is provided, thebattery 84 will typically only provide power for the electronic circuitswhen the internal power supply 82 is not energized by the AC line.Charging the battery 84 can be accomplished in at least two ways. Onemethod would be to disconnect the latching battery connector 80 from theinterface board, remove the battery 84 from the rear enclosure 22, andattach the battery 84 to an external charging device. This method hasthe advantage that batteries can be swapped quickly and the load cellindicator 10 placed back in service within several minutes. The morecommon method of battery charging is to provide AC power to theindicator, which will energize the internal power supply contained inthe rear enclosure 22. The power supply 82 is designed to simultaneouslypower the indicator electronics and charge the battery 84. This methodis commonly used for a semi-portable installation, where the usernormally provides AC power to the indicator 10 and only requiresportable operation on occasion.

In operation, a user will loosen the captive screw fasteners 40 toremove the rear cover 18 from the base 16, gaining access to the rearenclosure 22. The user will pass one or more cables 46 from measuringtransducers 48, such as load cells, through the ports 42, electricallyconnect the cables 46 to the terminal block style connector 76, andensure that the water resistant closures 50 are sealed to inhibit orprevent the entry of moisture through the ports 42 and into the rearenclosure 22. A battery 84 may be installed or replaced, or the batterymay be connected to or disconnected from the connector 80. The user thenmates the front and rear connectors 70 and 72 and fastens the rear cover18 to the base 16 using the captive screw fasteners 40 to compress theO-ring type seal and form a water resistant seal to inhibit or preventthe entry of moisture into the rear enclosure 22. If outside AC power isrequired, the user plugs the external power cord 44 into an outlet. Theuser may then set up the indicator 10 to provide the desired displayformat using the keypad 33 and the optoelectronic transceiver 60. Theuser may also enter or retrieve data or enter, revise, or replacesoftware routines or code using the keypad 33 and the optoelectronictransceiver 60. Although not preferred, it is understood that a user mayenter or retrieve data or enter, revise, or replace software routines orcode using other serial communications ports/channels, such as by usinga cabled connection to make an electrical connection to the interfacecircuit board 74 in the same manner load cells 48 are connected, toterminals on terminal blocks 76.

In this manner, the indicator 10 of the present invention overcomesweaknesses found in previous load cell indicators. For example, thepermanently sealed front enclosure 20 containing the main circuit board58 is protected from moisture and environmental contamination. The powersupply 82 is potted in epoxy 90 to prevent fluids from coming intocontact with the high voltage AC power supply 82. The usual causes ofkeypad 33 damage and wear are eliminated by the touch sensitive keypad33 circuit and rigid polycarbonate front panel 24. Reasonable batterylife, excellent display 28 visibility and readability, and long displaylifetime are provided by the choice of a backlit liquid crystal display.The display 28 is mounted in the permanently sealed front half of theenclosure, so there is no opportunity for display fogging orcondensation. The use of captive screw fasteners 40 to clamp the frontand rear halves of the indicator 10 allows for a technician to havequick access to the electrical terminals 76 for wiring external devices,such as load cells 48. The ability to interface with multiple load cells48 eliminates in most cases the need for external analog summing boxes.Connection to external data communication devices is facilitated bymultiple serial communication ports and the ability to quickly andeasily update the load cell indicator software. The software updatemechanism also allows for modifications should the indicator 10 beintegrated into other systems. The sealed front enclosure 20 is not userserviceable, so highly skilled technicians are not required totroubleshoot and repair the indicator 10.

Other modifications, changes and substitutions are intended in theforegoing, and in some instances, some features of the invention will beemployed without a corresponding use of other features. For example, theindicator 10 may include or omit a battery 84 or may include or omit anAC power supply 82. Further, the sealed front enclosure 20 may containany number of different combinations of elements and need not containall of the elements as described in the preferred embodiments discussedabove. Further still, although the above discussion related primarily toload cells 48 and load cell indicators 10, it is understood that thecontroller 10 of the present invention make take any number of differentconfigurations and may be used in connection with any number ofdifferent devices and measuring transducers 48. Also, although a touchsensitive capacitive keypad 33 is preferred, any number of differentkeypads 33 or data entry means may be used, and the keypad 33 may bedisposed in any number of locations, including externally. It is alsounderstood that the entire disclosure of U.S. Provisional PatentApplication Ser. No. 60/350,297, filed on Jan. 16, 2002, is incorporatedherein by reference. Of course, quantitative information is included byway of example only and is not intended as a limitation as to the scopeof the invention. Accordingly, it is appropriate that the invention beconstrued broadly and in a manner consistent with the scope of theinvention disclosed.

1. A device, comprising: a base; a first cover bonded to the base toform a watertight first enclosure; a second cover fastened to the baseto form a water resistant second enclosure; a first circuit boarddisposed within the first enclosure; a first connector electricallyconnected to the first circuit board; a display electrically connectedto the first circuit board, the display being disposed within the firstenclosure; a keypad electrically connected to the first circuit board,the keypad being disposed within the first enclosure; a second circuitboard disposed within the second enclosure; and a second connectorelectrically connected to the second circuit board, the first and secondconnectors being disposed to connect when the second cover is properlypositioned on the base.
 2. The device of claim 1, wherein: the bondcomprises a first adhesive bond; and the base and the first cover areadapted so that a user may not gain physical entry to the firstenclosure without breaking, cutting, or otherwise piercing the base orfirst cover.
 3. The device of claim 1, wherein the keypad comprises atouch sensitive, capacitive keypad.
 4. The device of claim 1, wherein:the first cover comprises a clear front panel; and a side panel bondedto the front panel; and further comprising a graphic legend, the graphiclegend being bonded to the front panel, and the keypad being bonded tothe graphic legend.
 5. The device of claim 4, wherein the front panelcomprises a rigid, transparent plastic, the front panel having at leastone area of reduced thickness adjacent the keypad.
 6. The device ofclaim 1, further comprising a potted, AC power supply disposed in thesecond enclosure and electrically connected to the second circuit board.7. The device of claim 6, further comprising a battery disposed withinthe second enclosure and electrically connected to the second circuitboard.
 8. The device of claim 1, further comprising an optoelectronictransceiver electrically connected to the first circuit board, thetransceiver being disposed within the first enclosure.
 9. The device ofclaim 8, wherein the optoelectronic transceiver comprises an infraredoptoelectronic transceiver.
 10. The device of claim 1, furthercomprising a plurality of captive screw fasteners, captively retained bythe base.
 11. The device of claim 1, further comprising an erasable,programmable, electronic memory device electrically connected to thefirst circuit board, the erasable, programmable, electronic memorydevice being disposed within the first enclosure.
 12. The device ofclaim 1, further comprising a measuring transducer, the measuringtransducer being disposed outside of the first enclosure and the secondenclosure and being electrically connected to the second circuit board.13. The device of claim 12, wherein the measuring transducer comprises aload cell.
 14. A load cell indicator, comprising: a housing defining afront enclosure and a rear enclosure, the front enclosure beingpermanently sealed to prevent fluid infiltration; a first circuit boarddisposed within the front enclosure; a first connector electricallyconnected to the first circuit board; a display electrically connectedto the first circuit board, the display being disposed within the frontenclosure; a keypad electrically connected to the first circuit board,the keypad being disposed within the front enclosure; a second circuitboard disposed within the rear enclosure; and a second connectorelectrically connected to the second circuit board, the first and secondconnectors being disposed to connect when the housing is assembled. 15.The load cell indicator of claim 14, wherein the keypad comprises atouch sensitive, capacitive keypad.
 16. The device of claim 14, furthercomprising a potted AC power supply disposed in the rear enclosure andelectrically connected to the second circuit board.
 17. The device ofclaim 14, further comprising an optoelectronic transceiver electricallyconnected to the first circuit board, the transceiver being disposedwithin the front enclosure.
 18. The device of claim 14, furthercomprising an erasable, programmable, electronic memory deviceelectrically connected to the first circuit board, the erasable,programmable, electronic memory device being disposed within the frontenclosure.
 19. A method, comprising: (a) placing a first circuit board,a display, and a keypad in a first housing; (b) bonding the firsthousing closed to form a first enclosure containing the first circuitboard, the display, and the keypad so that a user may not gain physicalaccess to the first enclosure without breaking, cutting, or otherwisepiercing the first housing; (c) electrically connecting the firstcircuit board to a second circuit board; and (d) electrically connectingthe second circuit board to a measuring transducer.
 20. The method ofclaim 19, wherein: step (b) comprises adhesively sealing the firsthousing closed to form a first enclosure containing the first circuitboard, the display, and the keypad so that a user may not gain physicalaccess to the first enclosure without breaking, cutting, or otherwisepiercing the first housing; and further comprising placing the secondcircuit board in a second housing and affixing the second housing to thefirst housing.